This disclosure relates generally to semiconductor manufacturing, and more particularly to a method for manufacturing a metal gate.
A gate dielectric integrity of metal-oxide-semiconductor field effect transistor (MOSFET) is associated with reliability and lifetime of MOSFET devices. As the gate dielectric thickness is reduced in technology scaling-down, gate leakage is induced, increasing power consumption and reducing device performance.
High K materials, which include materials with K values larger than approximately 5, such as SiON, HfOxSiy, or HfO2, are implemented to realize thicker gate dielectric layers for minimized leakage current and equivalent oxide thickness (EOT). Also, a metal gate electrode can be used to reduce gate resistance. In addition, the metal gate can also reduce gate leakage that is induced by boron penetration from polysilicon gate electrodes.
On metal gate formation, problems include many processing issues such as chemical mechanical polishing ending point detection, spacer and liner loss, and poly gate loss. On source and drain contact formation, problems include shallow trench isolation loss and spacer oxide liner loss. In general, the process involves complex steps that increase cost.
Accordingly, it would be desirable to provide an improved method for manufacturing a metal gate absent the disadvantages found in the prior methods discussed above.